The present invention relates to light based communication links, and more particularly, to a self-aligning communication link for connecting computer-based devices.
Infra-red (IR) communication links are now provided on many computers and devices designed to communicate with computers or with each other. An IR communication link utilizes an IR transmitter and receiver on each device for sending and receiving digital light signals, respectively. Each IR module consists of an IR transmitter, typically a light emitting diode, a photodiode, used to receive the light signals, and electronic circuitry for signal processing and control. The three components are small, relatively simple, and produced in high volumes. Hence, the IR module is generally a very inexpensive component. To establish the IR link, the user aligns the two devices such that the IR transmitter in the first device is aligned with the IR receiver in the second device.
In principle, IR communication links provide an attractive alternative to wires for connecting these devices both in terms of cost and convenience. For example, digital cameras typically include an IR communication link for downloading pictures taken by the camera to a computer. IR communication links have also been used for connecting computers together in networking systems and computers to printers.
While IR communication links have great potential, they have not found wide acceptance among users. As noted above, to initiate a communication between two devices via an IR communication link, the IR transmitter and receiver of the first device must be aligned with the corresponding receiver and transmitter of the second device. In practice, the devices must be aligned to within 20 degrees both horizontally and vertically. This often requires more time and effort than most users are willing to invest. Hence, the IR communication links are seldom used.
In addition, if the devices are to communicate over a distance greater than about 1 meter, the alignment tolerance must be even greater. The light emitting diodes (LEDs) used to generate the IR light signals have an intensity distribution that decreases with the angle from the central ray of the light beam. Hence, when the devices are mis-aligned, the light intensity available for sending and receiving signals decreases. The maximum communication distance is determined by the light intensity available to each device. Hence, mis-aligned devices have reduced range. In principle, the intensity of the transmitters in the IR devices can be increased; however, various safety, battery-life, and cost considerations limit the maximum intensity of the light beam. Accordingly, devices that are mis-aligned by 20 degrees are limited to a communication path of less than one meter.
Broadly, it is the object of the present invention to provide an improved IR communication port.
It is a further object of the present invention to provide an IR communication port that is self-aligning.
These and other objects of the present invention will become apparent to those skilled in the art from the following detailed description of the invention and the accompanying drawings.
The present invention is an optical port with directional control. The port includes a transmitter, receiver, and first actuator. The transmitter generates an outgoing light signal that propagates in a transmission direction in response to an outgoing electrical signal. The receiver receives an incoming light signal and generating an incoming electrical signal therefrom, the receiver having a reception direction aligned with the transmission direction. The first actuator alters the transmission direction of the outgoing light signal in response to a first control signal. In one embodiment, the first actuator determines the direction of the outgoing light signal in a first plane, and a second actuator controls the direction of the outgoing light signal by an amount determined by a second control signal. The second actuator controls the direction of the outgoing light signal in a second plane that is orthogonal to the first plane. The actuators can be constructed from beam deflectors that utilize moveable mirrors to alter the transmission direction. In one embodiment, the deflector includes an array of mirrors, each mirror rotating about an axis through the mirror. Actuators that rotate the transmitter and reflector may also be utilized.